In traveling-wire electroerosion machining, the machining liquid, customarily a distilled water liquid, must be continuously supplied and replenished into the cutting region to play important distinct roles, viz. to serve not only as the machining medium to continuously renew the electroerosive action, but as a flushing medium to continuously remove the erosion machining products and contaminants from the cutting zone and at the same time as a coolant to prevent the traveling wire electrode and the workpiece subjected to the high-energy electroerosion cutting action from being excessively heated. thus it is necessary to supply and replenish the machining liquid in the form of a continuous stream into the cutting zone.
To this end it has been customary to employ a nozzle designed to inject into the cutting zone the machining liquid in a stream of relatively high velocity or to provide more than one such nozzle in the region of the workpiece which is customarily disposed in the atmosphere, the stream or streams of the machining liquid being oriented toward the cutting zone or relatively thin continuously developing groove. For example, it has been found to be advantageous to use a pair of injection nozzles arranged to be coaxial with one another and with the traveling wire electrode in such a manner that one nozzle is disposed on one side of the workpiece and the other nozzle on the other side of the workpiece. In such an arrangement, two independent streams of the machining liquid are forced from the opposite sides of the workpiece into the cutting zone and are allowed there to join to flow out through the cut groove behind the cutting zone in the workpiece.
I have now found that the prior nozzle arrangements used in traveling-wire electroerosion machining are not entirely satisfactory to allow a desired cutting speed and accuracy to be obtained. Cooling and flushing tend to be insufficient, particularly in the area in the cutting groove where the two streams injected from the opposite sides of the workpiece join. Furthermore, the ambient air tends to be drawn into the stream ejected from each nozzle towards the thin cutting groove so that entrapped gas bubbles occupy a substantial volume of the machining liquid traversing the passage in the cutting region. It has now been found that this uncontrolled aeration substantially reduces the cutting speed and accuracy and may also be a significant cause of machining instability and the undesirable breakage of the traveling wire electrode.